this is just my hunch but maybe MC died in this timeline and got reincarnated soon thereafter. Fate would bring them together again but ML would still be in love with her past self. That's why her rival in the 19th life is herself's 18th life. Which is why the title is take care of me again in this life. Which means ML, who exists in the present, was a part of her past life and her present life, hence the use of "again." Which means she's much younger than ML in her 19th life lol. I'm really curious how they would meet again after she reincarnated. I actually thought they both died or something but I realized he looks exactly the same as well as his circumstances (he still looks like the son of the CEO or the CEO himself in the cover arts). Only the girl's appearance changed, and it's not just the color of her hair. She also fell in love with the ML pretty fast (chapter 2) so that's definitely not a good sign. This work is so interesting!